Birthdays come and go but a life lit up by a thousand full moons is more occasion for celebration. So this year around, Vajpayee’s birthday celebrations will come around a month late — on January 14, full moon day for Makar Sankranti.BJP general secretary Pramod Mahajan, after some painstaking number-crunching, has concluded that Vajpayee, born 81 years ago on December 25, will see his 999th full moon tonight. And 30 days from now, he will touch the magic figure of 1000 — an occasion traditionally celebrated in southern and western India, says Mahajan. A ‘‘sahasra chandra darshan’’ will be hosted on the lawns of his Lutyens Bungalow on January 14, with a special recital by Pandit Jasraj. On the guest list — President Abdul Kalam, vice-president Bhairon Singh Shekhawat and Prime Minister Manmohan Singh who have already accepted the invitation. Congress chief Sonia Gandhi will also be invited. —Manini Chatterjee